US7849121B2ExpiredUtilityPatentIndex 84
Optical-based, self-authenticating quantum random number generators
Assignee: HEWLETT PACKARD DEVELOPMENT COPriority: Apr 20, 2006Filed: Oct 10, 2006Granted: Dec 7, 2010
Est. expiryApr 20, 2026(expired)· nominal 20-yr term from priority
H04L 9/0858G06F 7/588G06F 7/58G01R 15/22B82Y 10/00H04L 9/0662H04L 9/32H01S 3/00
84
PatentIndex Score
12
Cited by
6
References
19
Claims
Abstract
Various embodiments of the present invention are directed to methods and systems for generating random numbers. In one embodiment, a quantum random number generator comprises: a state generator configured to generate a quantum system in a coherent state; a polarization states analyzer configured to project the quantum system onto one of four different polarization states, and detect each of the four different polarization states; a raw bit generator configured to convert the quantum system into a single photon and detect the single photon in either a first polarization state that corresponds to a first binary number or a second polarization state that corresponds to a second binary number; and a system control configured to receive signals from the polarization states analyzer and the raw bit generator, the signals corresponding to the polarization states, and output a random number based on the first and second polarization states of the single photon.
Claims
exact text as granted — not AI-modified1. An optical-based, self-authenticating random number generator comprising:
a state generator configured to generate a quantum system in a coherent state;
a polarization states analyzer configured to project the quantum system onto one of four different polarization states, and detect each of the four different polarization states;
a raw bit generator configured to convert the quantum system into a single photon and detect the single photon in either a first polarization state that corresponds to a first binary number or a second polarization state that corresponds to a second binary number; and
a system control configured to receive signals from the polarization states analyzer and the raw bit generator, the signals corresponding to the polarization states, and output a random number based on the first and second polarization states of the single photon.
2. The system of claim 1 wherein the state generator further comprises one of:
a laser diode;
a light bulb; and
a light-emitting diode.
3. The system of claim 1 wherein the quantum system further comprises a pulse of electromagnetic radiation.
4. The system of claim 1 wherein the polarization states analyzer further comprises:
a first beamsplitter configured to split the quantum system into a first reflected quantum system and a first transmitted quantum system, the first reflected and the first transmitted quantum systems both in a first polarization state;
a second beamsplitter configured to split the first transmitted quantum system into a second reflected quantum system and a second transmitted quantum system, the second reflected and the second transmitted quantum systems both in the first polarization state and the second transmitted quantum system directed to the raw bit generator;
a half-wave plate configured to receive the first reflected quantum system in the first polarization state and output the first reflected quantum system in a second polarization state;
a quarter-wave plate configure to receive the second reflected quantum system in the first polarization state and output the second reflected quantum system in a third polarization state;
a first polarization beamsplitter configured to split the first reflected quantum system into a first horizontally polarized quantum system and a first vertically polarized quantum system;
a second polarization beamsplitter configured to split the second reflected quantum system into a second horizontally polarized quantum system and a second vertically polarized quantum system; and
four photodiode detectors, each photodiode detector configured to detect one of the horizontally and vertically polarized quantum systems.
5. The system of claim 1 wherein the polarization states analyzer further comprises:
a beamsplitter configured to split the quantum system into a reflected quantum system and a transmitted quantum system, the reflected and the transmitted quantum systems both in a first polarization state and the transmitted quantum system directed to the raw bit generator;
a concave lens configured to receive the reflected quantum system and output a divergent quantum system;
a quadrant polarization filter configured to receive the divergent quantum system and output four quantum systems, each of the four quantum systems in one of four polarization states; and
a quadrant photodiode detector configured to separately detect each of the four quantum systems in the four polarization states.
6. The system of claim 1 wherein the raw bit generator further comprises:
an attenuator configured to convert the quantum system in the coherent state into either the vacuum state or the single photon, the single photon in a linear superposition of orthogonal first and second polarization states;
a polarization beamsplitter configured to transmit the single photon in the first polarization state and reflect the single photon in the second polarization state;
a delay fiber connected to the polarization beamsplitter and configured to transmit the single photon in the second polarization state; and
a single photon counting module configured to detect the single photon in either the first polarization state or the second polarization state and output a corresponding signal to the system control.
7. The system of claim 1 wherein the signals output from the polarization states analyzer and the signals output from the raw bit generator are synchronized.
8. The random number generator of claim 1 wherein the system control receives signals output from the polarization states analyzer, each signal representing detection of one of the four different polarization states, receives signals output from the raw bit generator, each signal representing the polarization state of the single photon, and performs tomographic analysis to authenticate the randomness of the signals output from the raw bit generator.
9. An optical-based, self-authenticating random number generator comprising:
a state generator configured to generate a quantum system in a coherent state;
a beamsplitter configured to split the quantum system into a number of separate quantum systems, each of the separate quantum systems in the coherent state;
polarization filters, each polarization filter configured to project one of the number of quantum systems onto a unique polarization state;
a first attenuator configured to attenuate a first of the number of quantum systems to either a vacuum state or a single photon state and a second attenuator configured to attenuate a second of the number of quantum systems to either a vacuum state or a single photon state;
photodiodes, each photodiode configured to detect one of the number of separate quantum systems; and
a system control configured to receive a signal output from each of the photodiodes, each signal representing detection of one of the number of different polarization states, and output a random binary number.
10. The system of claim 9 wherein the state generator further comprises a laser diode.
11. The system of claim 9 wherein the quantum system further comprises a continuous wave of electromagnetic radiation.
12. The system of claim 11 wherein the two avalanche photodiodes are configured to detect the first and second of the six quantum systems, and the four PIN photodiodes are configured to detect the four remaining quantum systems.
13. The system of claim 9 wherein the six photodiodes further comprise two avalanche photodiodes and four PIN photodiodes.
14. A method for generating a sequence of random binary numbers, the method comprising:
generating a quantum system in a coherent state;
splitting the quantum system into a number of separate quantum systems, each quantum system in a coherent state;
projecting each of the separate quantum systems onto one of a number of different polarization states;
detecting and storing the polarization state of each of the separate quantum systems;
repeating the steps of generating, splitting, projecting, and detecting to construct a raw sequence of binary numbers, the raw sequence of binary numbers based on the polarization states of two of the separate quantum systems; and
based on the stored polarization states of each of the separate quantum systems, performing tomographic analysis in order to extract and output a sequence of random numbers from the raw sequence of binary numbers.
15. The method of claim 14 wherein splitting the quantum system into a number of separate quantum systems further comprises transmitting the quantum system through one or more beamsplitters.
16. The method of claim 14 wherein projecting each of the separate quantum systems further comprises transmitting each of the separate quantum system through a corresponding polarization filter.
17. The method of claim 14 wherein performing tomographic analysis further comprises constructing the minimum entropy:
H
Min
(
ρ
^
S
)
≡
-
log
2
(
max
x
∈
ρ
^
S
P
r
(
x
)
)
where
{circumflex over (ρ)} s is the density matrix for an ensemble of states |ψ i =c i |H +d 1 |V as a function of Stokes parameters;
Pr(x) is the probability of a event x; and
max
x
∈
X
Pr
(
x
)
Pr(x) means the maximum probability Pr(x) over every event x in X.
18. The method of claim 17 wherein performing tomographic analysis further comprises constructing a Toeplitz matrix T n×m based on the minimum entropy H Min ({circumflex over (ρ)} S ), where m is the number of random binary numbers, n is the number of raw binary numbers, and m<n.
19. The method of claim 17 wherein the density matrix further comprises:
ρ
^
S
=
1
2
∑
i
=
0
3
S
i
S
0
σ
i
=
1
2
[
1
+
S
3
S
1
-
ⅈ
S
2
S
1
+
ⅈ
S
2
1
-
S
3
]
where
(S 0 , S 1 , S 2 , S 3 ) are Stokes parameters;
the Stokes parameter S 0 is normalized to “1”; and
σ 1 , σ 2 , and σ 3 are the Pauli matrices.Cited by (0)
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